Credit: ABC Family

Big "A". Red Coat. The sicko in charge of it all. Whatever you want to call her (or possibly him), the Liars' greatest threat is still a mystery on Pretty Little Liars, which means every episode is a new piece of the puzzle. Who do we think "A" could be after Season 4, Episode 3: "Cat's Cradle"? We've gathered our top suspects.

3. Wren Kingston

Why he might be Big "A": As we learned this week, there are a lot of question marks around what happened to Toby's mom at Radley, and who do we know in a better position to dig up — or cover up — goings on at Rosewood's mental hospital than the doctor who works there? Plus, in the "A" tag, we saw that "A" has gotten his/her hands on Emily's scan from her injury. Again, Wren is really the only person we know in a position to easily mess with medical records.

Why he might not be Big “A”: We're still missing the why for Wren. As we speculated last week, maybe he's the mysterious "beach hottie." Right now, that's the only reason we can think of for him to stalk the Liars. You know, unless he's just crazy for crazy's sake.

2. Melissa Hastings

Why she might be Big "A": Let us count the ways. As we've said before, Melissa has plenty of reasons to hate the Liars, and she's clearly tangled up in this mess somehow. This week didn't make her look any less guilty. Between the fact that there's now a Melissa mask in play (and we know how "A" loves masks), her convenient disappearance right when everything was going down (who's to say she was really in DC?), and her creepy conversations with Spencer, we trust her less than ever, which is to say not at all.

Why she might not be Big “A”: While we definitely think Melissa is up to something, we get the sense that, as domineering as she is, she might also be scared herself. While we can see Melissa being Big "A", we can just as easily imagine that she (and probably the rest of the so-called "B" team) is another pawn in "A"'s game. We're pretty positive Melissa knows something about Ali's death/disappearance, but if we're right, it's very possible "A" is holding that over her head.

1. Alison DiLaurentis

Why she might be Big "A": As we've said before, until we get definitive proof that she's dead, Ali is going to remain at (or at least near) the top of our "A" suspect list, for all the reasons we've discussed before. The fact that Ali had Ali masks made back before she "died" just adds one more reason to be suspicious. We know she had those masks, so who's to say she doesn't go around as Red Coat wearing them as a way to protect her identity? After all, nothing throws people off the scent like pretending to be yourself.

Why she might not be Big “A”: We sound like a broken record, but again: She's supposedly dead. We guess we shouldn't discount that.

Of course, these aren't the only people we have our eyes on (we even considered Ashley Marin, but we just can't bring ourselves to think that yet. We love her too much!). In Rosewood, anything is possible.

Who do you think "A" is? Sound off in the comments below!

Catch the next episode of Pretty Little Liars on Tuesday, July 2, 2013 at 8 p.m. ET/PT on ABC Family.